The 9-Word Subject Line Rule
Subject lines under 9 words get opened. Subject lines over 12 words get ignored. The data is crystal clear: brevity wins.
Winning subject line formulas:
- "Quick question, {{first_name}}" (5 words, 28% open rate)
- "{{company}} + {{your_company}}" (3 words, curiosity-driven)
- "Idea for {{company}}" (4 words, value暗示)
- "Are you using {{competitor}}?" (5 words, pain point)
Avoid: ALL CAPS, excessive punctuation (!!!), spam words (free, guaranteed, act now), and emojis in B2B.